The present invention is directed to a solenoid apparatus and more particularly to a solenoid apparatus using a magnetic material yoke as the electrical ground.
A conventional solenoid apparatus is usually provided with a metal casing in which are incorporated a bobbin having a coil, a magnetic material core, a magnetic material plunger and a magnetic material yoke. In such a conventional solenoid apparatus, one end of the coil is usually connected to the casing so that the casing can be used as the ground line thereby reducing the number of wiring connections and assembling time. Generally, one end of the coil is connected to the casing by soldering or clinching, using an insulated lead wire.
In Japanese Utility Model Published Application No. 5956713, which is assigned to the same Assignee as the present application, it was proposed to form a resilient projection on the ground terminal of the coil which extends into resilient contact with the casing to electrically connect the projection to the casing by a subsequent clinching operation.
In recent years, the metal casing of conventional solenoid assemblies has been replaced by a casing made of synthetic resin material because of the lower cost. In such a case, it is not possible to use the casing as the ground line and therefore, a separate lead wire must be provided for the ground which must be connected to the common ground line such as a grounded body upon assembling of the solenoid. As a result, there are drawbacks since the number of wires and the assembling time are increased.